Wednesday, August 01, 2012

Water and Energy, a Critical Connection

US Person continues the drought theme with a look at the vital if not apparent connection between water and power production. According to the Union of Concerned Scientists, of all the ways we use and misuse water in America, power plants use the most at 41% of our freshwater needs. That exceed the obvious agricultural uses at 37%. Of all power generation sources nuclear power plants require the most water to make steam, cool reactors and store spent but still radioactive fuel rods. A lot is lost to the atmosphere, that is what happens in the large towers some people mistake for the reactor itself, but most is returned to rivers and estuaries at elevated temperatures often detrimental to aquatic life. The bottom line is power plants need a continuous supply of clean water to operate near full capacity. Last year's heat wave in Texas caused the the water levels in Martin Creek to fall so low that water had to be pumped from the Sabine River eight miles away so Luminant power company could operate its local coal fired plant. Intake water that is too hot can cause problems for a power plant too. The two unit nuclear plant at Prairie Island, MN had to reduce output by 50% to compensate for the elevated temperature of the Mississippi River during the 2006 heat wave. Browns Ferry nuclear plant has reduced generation output in three of the last five summers because it was producing water too hot to be released to the Tennessee River. TVA is spending hundreds of millions for a new cooling tower, the cost of which will be passed to ratepayers.

The new nuclear units proposed for Southern Company's Vogtle nuclear facility along the Savannah River [photo] are estimated to use 55-88 million gallons of water per day, 50-75% of which will be evaporated. The two existing and two proposed reactors could use enough water to meet the needs of 1.4 to 2.3 million Georgians. If you look at the Drought Monitor map posted below, central Georgia is in the midst of an extended, extreme drought. Thermoelectric plants in Georgia already use the most water of any sector in the state. Profligate use of water resources is not a sustainable practice, even in the United States. Solar and wind power require virtually no water to operate, leaving some for you and me and other Earth creatures to drink.